Bombing instrument for aircraft



Sept. 9, 1952 E. A. WILKENSQN ETAL BOMBING INSTRUMENT FOR AIRCRAFT Filed001;. 5, 1949 9 Sheets-Sheet 1 Fig. I

v -167 m/ 600 kill/h 373 m.p.h.

Sept. 9, 1952 E. A. WILKENSON EI'AL 2,609,729

BOMBING INSTRUMENT FQR AiRCRAFT Filed 001;. 5. 1949 9 Sheets-Sheet 5Z2?/ 2) ere/C P Se t; 9, l952 a. A. WILKQNSON ETAL 2,

BOMBING msrRuMENT FOR AIRCRAFT Filegl Oct. 5, 1949 9 Sheets-Sheet 4akumfiw Ink .AZvar T Vilkan an Tar Zen Taxen' Filed Oct. 5, 1949 9Sheets-Sheet 5 P 1952 E. A. WILKENSON ETAL 2,609,729

BOMBING INSTRUMENT FOR AIRCRAFT B 77 52" Tar silen TaxE n "f wi $6 E. A.WILKENSON ETAL BOMBING INSTRUMENT FOR AIRCRAFT Sept 9, 1952 Filed Oct.5. 1949 P 1952 E. A. WILKENSON ETAL 2,609,729

BOMBING INSTRUMENT FOR AIRCRAFT Filed Oct. 5. 1949 9 Sheets-Sheet 711210 ez i Z'JZ .Isfz) Llrarbdozv Ti Fax zz/ Sept. 9, 1952 E. A.WILKENSQN ETAL 2,609,729

BOMBIING INSTRUMENT FOR AIRCRAFT Filed on. 5, 1949 9 Sheets-Sheet 8 IIIIII 0/856 7/0 mam V lrLv enters .Z'. d .HL bjrelusolz,

P 1952 E. A. WILKENSON ETAL 2,609,729

BOMBING INSTRUMENT FOR AIRCRAFT 9 Sheets-Sheet 9 Filed Oct. 5, 1949.fllzlllccizusazv p /wm Patented 'Sepi. 9, 1952 UNITED STATES PATENTOFFICE BOMBING INSTRUMENT FOR AIRCRAFT Erik Alvar Wilkenson and PerTorsten Faxn,

Linkoping, Sweden, assignors to Svenska Aeroplan 'Aktiebolaget,Linkoping, Sweden stock company of Sweden v a joint- Application October5, 1949, Serial No.. 119,7 08 i In Sweden August 4, 1941 puting theexactattitude and direction of flight path of a bombing aircraft during thepull-out :from a 'dive in which a fixed opticalsight in the' aircrafthas been aimed on the target; for integrating and correlating that datewith manu- :allyinserted data relating to known factors which affect thebombing situation; and for' automatically effectin release of'a bomb atthe critical instant in which the aircrafts attitude and flightdirection are such as to impart to the bomb a trajectory whichwillintersect'the target.

This application embraces thesubject matter of our copending abandonedapplicationserial No. 731,164, and comprises a continuation-inpart ofour copending' application, Serial No. 731,163. H A

' In general, when" abomb or other comparable I object is released froman aircraft with the purpose'of hitting agiventargeathere is no initialspeed of ejection'of the bomb in relation to the aircraft. The bomb andthe aircraft have, therefore, the same velocity and direction of motionat the moment of release.

Owing to the force of gravity the path of the falling bomb will be moreor less curved in a verticalplane. It follows that the direction of themotion of the bomb, and of the aircraft, at the moment of release,cannot coincide with the aimingline, i. e. the straight line between thetarget andthe' aircraft, if a direct hit is to be obtained. The angle 5between the aiming line and the direction which the bomb must have atthe instant of release to'achieve a hit will be called'the angle ofdivergence in'the following text. 'See Figure l of the accompanyingdrawing, in which I is the ground, 2 is a fixed target,

and 3 is an aircraft from which a bomb is to be released. At the momentof release of the bomb the aircraft is at the height it above theground, and is flying with a velocity v in the, direction shown by thearrow 4'. At the moment of release, the connectingline ifromtheaircraft. to. the targetmakes the angle withjthe hori- ,zontal 'plane:The angle between the arrow 4' into account.

and the connecting line 4 is the angle of divergence 6.

The magnitude of the angle e necessary for a. hit is primarily dependenton the above men tioned factors h, o and (p or corresponding'quane Otherfactors such as wind, temperature tities. and barometric pressure etc.,must also be taken used herein.

The two principal methods which are used for bombing from aircraft are.level bombing and Ydive bombing. As the names imply, the chiefdifference is that in the former method the. aiming and release of thebomb occurs during hori I zontal flight, and in the latter in a dive. Inall cases, however, the bomb must be released when the appropriate valueof the divergence angle e has been attained. This is determined by meansof instruments or by judgment.

There are manykinds of bombing devices or bomb sights, and they have incommon the object of calculating the correct value of ewith regard tothe prevailing elements of aim. These 'quantitiesfare introduced bymanual adjustments, o'ri' ar automatically measured by specialauxiliaryl'; The elements of aim can also be standardized to, someextent to certain va1ues,'f

instruments.

but in that case the bombing device is limited these values.

Level bombing is more suitable than dive V bombing in some cases, andvice versa; as a rule the former method is used for heavy aircraft-andthe latter for lighter ones. Furthermore, it is is usual that the pilotaims and releases "the bomb in the case of dive bombing, while a specialbomb aimer relieves the pilot of these duties in level bombing.

considered in the following.

There are two well known types of bomb sight In the first 't pethe'optical axis of the sight is fixed inthe aircraft or is manuallyadjustable, andvin using it the pilot usually has to aim with acertain'amount" in use for dive bombing.

of allowance for divergence, according to'stirna-f tions: of theprevailing elements of aim. ,In the second type an automaticallycomputing instrument moves the optical axis according to continuousmeasurements of at least the most important elements of aim, therebyrelieving the pilot to some extent. r H Dive bombing methods can bedivided into dif- As a common term to cover all the variables whichinfluence. the angle of divergence, the expression elements of aim" Willbe As the invention which will be f dealt with here is a bombing devicefor use, in" dive bombing, only that type of bombing will be pointinterms of the attitude and direction and velocity of motion of thebombing aircraft,

its lateral axis. -An. attack made across the .in practice of asatisfactory degree of accuracy presents no great difi'iculty. a

With a bombing instrument of suitable design, the pull-out methodpermits very accurate bombing even at long target ranges, because it isnot limited to small values of the angle 6. up to 6 30 for example, areutilized, it will be seen from Fig. 2 how the size of the region aroundthe target increases, from which the bomb can be released. r

In some bombing instruments, old in the art, for instance that disclosedin a patent toMorgenthaler et al., Number 2,410,097, the direction ofmotion of the aircraft is determined by correlated measurements of thespeed. of the aircraft and the rate of change of its altitude. Thatexpedient obviously gives satisfactory accuracy onlyas long "as saidrate of change is small compared with said speed, i. e. for shallowdives (glides). In other bombing instruments, old in the art; thedirection of motion is standardized as a function of thetime after thestart of a pull-out. Suchinstruments, of course, are limited in theirutility and give poor results when employed outsidethe restricted rangeof conditions for whichjthey aresu ited.

By contrast, itis an object'of this invention to provide a bombinginstrument for use in dive bombing which will automatically release abomb at theproper point during the pull-out from an aiming dive to.achieve a hit on a target aimed at during the dive, and which may besuccessfully used under widely varying conditions of elements of aim.

Another object of this invention resides in provision of a bombinginstrument for precision If values bombing in the pull-out of. adivebombing dive,

which instrument will automaticallydetermine and correlate all of thesignificant variable elements of aim during the period from the instant.when the bomb-aimer-pilot ascertains that a .fixedaxis of his aircraftcoincides with the line of sight to the target and manually initiatesoperation of the instrument, to. the instant during the pull-out whenthe bomb must bereleased to hit the target, at which instant theinstrument effects such release.

V A further object of this invention resides in the provision ofcomputing instrumentalities for automatically correlating and computingthe elements of aim involved in bombing in the pull-outfrom; a divebombing dive and'deterrninin'g the; release Still another objectof. thisinvention resides in the provision of a computing device whichthree-dimensional camscan be utilized for automatic determination of thepoint at which a bomb should be released, under the conditions, above abomb to hit a target, under any of a wide range and variety ofconditions of speed, altitude, dive angle and rate of pull-out.

With the above and other objects in view, which vention resides in thenovel construction, combination and arrangement of parts substantiallyas hereinafter described and more partic'ul'arlydefined bythe appendedclaims, it being understood that such changes in the precise embodimentsof the herein disclosed. invention may be made"as craft in a divebombing pass and the trajectory of a bomb dropped from the aircraft. v

Fig. 2 is a chart showing the angle of divergence e as a'function of thealtitude of release of the bomb and the angle of dive for a certainspeed of flight ofan aircraft.

Figs. 3 and are diagrammatic side viewed the path of an aircraft and ofa bomb, said bomb being released in the pull-out of a dive. j

Fig. 5 is a schematic block diagram showing the interrelationof theprincipal components of the bombing instrument of this invention and thegeneral'manne'r .in which the several elements of aim are measured andintegrated.

' of the invention.

Fig. 7schematica1ly illustrates an arrangement of the principalcomponents of the bombing instrurnent.

Fig. 8 is a diagrammatic side View of an'aircraft having a bombinginstrument according to our invention.

Fig. 9 is a top view of one embodiment of our invention, having agyroscopefor angular references, aneroid means for altitude and speedcorrections and an accelerometer for angle of incidence correction.

Fig. 10 is a top View illustrating an alternative embodiment ofa'portion of the instrument of Fig. 9 with two gyroscop'es for angularreferences.

Fig. 11 is a top View of another embodiment of our invention, having agyroscope for angular references, radar means for slant range and speedcorrections and a vane for angle of incidence correction.

In the drawings like reference characters refer to like partsthroughoutthe several views- The bombing instrument according to the in-,vention, as shown in Fig. 8, consistsof a main and an auxiliary controlunit 22; containing a will appear as the description proceeds, thisinnumber of controls, adjusting devices, etc. The auxiliary control unitis intended for manipulation by the pilot, and is connected with themain unit by electrical or other means.

A bombing attack would be made as follows: The aircraft, which has abomb sight or gun sight with a fixed optical axis 20, is brought into adive. Maneuvering the aircraft so that the optical axis 20 intersectsthe target, the pilot presses an actuating button 23, Immediately afterthis he finishesthe dive by means of a normal pull-out. The actuatingbutton actuates the above mentioned main unit of the bombing instrument,which starts working. When the pull-out has advanced to a stagedetermined by the main unit, an impulse is given automatically to thebomb release mechanism 24 thus releasing the bomb 3|. The bombinginstrument, the design of which will appear below, corrects for allessential factors and the bomb therefore hits the target.

As will appear hereinafter, one of the essential factors which theinstrumentemploys in effecting its purpose is the position in space ofthe aircraft of minor importance, the function (i) gets the ,Fordeducingthe function (iv) ,the formula for e will first be given. in theparticular case where i e. an ideal case is assumed, where the infiuencand ft is g'dama mn o of onlyj two vari sures can be obtained from aPitot Static tube Neglecting other influencing'variables, as being forme=f(a', h, '17, 1.1,, (iv) e of wind and air resistance areneglectedfThe fideal angle of divergence 61 is given by the followingequation g =acceleration ofgravity 20 pull-out Obviously the angle 61can be written, e fofl/ Y) 4v) where I Zgh ables, viz, a and Y. r Therealistic formula of 9 can be put inthe form By mathematical, treatmentof the formulae it i can be shown-that the partial derivatives can i beexpressed with very good accuracy in the Using the quantity q thefollowing relation is also obtained This relation (x) enables the use ofanaccurate andrelatively simple method for determining the quantity Y,based on pneumatic measurements. Thus one embodiment of the instrumentis designed according to said relation and assumes that the staticpressure p and theimpact pressure qs are-available in the aircraft.'Said presinstalled in the aircraft, which may be the same as'thatnormally existing in every aircraft.

" The following relationships exist.

p w arer-. 1

where (level =the ratio of specific heat at constant pressure tospecificheat at constant volume for'iairfif- It should be noted fromEquations xi andxiithat the-quantities wit and q (in contrast to the,altitude h and speed '1) themselves) are both independent of thetemperature Tof the air. Further the influence of the temperature,gradienta is slight. By using h and q, therefore,.no devices fortemperature correction are necessary.

The angle of attack d in Equation iii is calculated in accordance withthe following aerodynamic formula: 7 H

, f q tr (e11) where p G=gross weight of the aircraft,

F=wing area, n=load factor=the acceleration of the aircraft where,asshown in Fig.4

=the angle between the optical axis '10 of'the sight and the horizontalplane, said angle being equal to s when aiming at the target.

Thus, from Equations iii, ix and xiv:

e =-.-a+a+ +ac+t (XV), Referring now to Figure 5'for a schematic diagramof the instrument, by which the several operations performed thereby maybe readily visualized in their relation to one another, each circlerepresents a component element of the instrument, such as a measuringdevice, a computing device, a control device, or some other calibratedunit, and the lines joining thecircles represent the transmissionsbetween the elements or, in other words, the ouputs of the elements from.Which the lines extend and the inputs to the-elements toward which theyextend. All of the component parts of the instrument, with the exceptionof those control devices which must be manually adjusted, workautomatically, and

' when the output result from some one kindof unit or element (e. g., agyroscope) is required'in several places in the instrument, thecorresponding symbol isrepeated at the corresponding places in thefigure. The wing loading of the aircraft G/F is assumed to be known andis introducediinto theinstruamet ment by a manuaLcontrQIL-MS :whichiszmeferably'graduated-in weight units: ,ifllheacceleration n isdetected and measured byiamaccelerometer 310 and the dynamic ainpressureq is a manom- 12 z-through.arirarc'corresponding toi-a :Ie: andzthezatmsa has; swung-.athroughaanarcim'zthenawozarmsze brought into coincidenceand a contact between Hthem may beiestablished .-zwhereby a bomb maymeter 3 which is pne mati c ted w eanhereleasedr the Pitot-static tubeof the aircraft. The outi of gthe acce1e r0meter androfwthe manometerare respectively fed-.intoa. calculator 308, the output of which ismodified by the wing loading setting on the control knob dOB. .ilheoperationr thist alcula or. wi l+ se yt e des r beds de ail-zs ilificestzto A P t etitsroutb s a io .oiith qefh-fin sfli E-sdescribed and-:;is,;thu s.;a ctio n. off the angle of attack a. i Six-111e,! an lemtidre senee .;is.-oht.a ned .oe yaluated by a calculating mechanism 3 I aitozazsf swab, 12', gal. Th

theaheightm irele se. sth iw ndspeedwtu as, significant vari blesand-the other; elementsof im an either neglected assumed to beconstant,ite ers izes e '.i n t h ver b ing the; Fqrmula vi it-is-possible-to fifelieensi me eioml e n E15 account. In this instance atthe moment of erelease altitude are taken i tliemodind embodiment: the instrument ofthis inventionschematically represented "in Figure 6, only one gyroscope3l4 is-employed, but t t-(pe forms three iunct ons. and. i there or r:10.vre ntedc n t ree places ime efieure. ..In th s ..embod m nt t i Qizontal-is. u edfas. ar i ren datum line, rather than the si l ililig111.the.-t the angle '6 which the sighting line makes with r the horizontalmust be eontinuoiji'slyetaken;jinto 7 pressinggthe button andathemQIldition E+a=rp.e I

must be satisfied at the instant of bomb release. The angular position;gi of the gyroscopeatth .-.;-.m mentto:ain.ing-.(Lieaaathe.momenttlieliutton is pressed) is first transmitteddirectly;.to the release impulse mechanism 306. Thegyroscope" alsotransmits to the' calculator 312 tan output relatejahe-altitudehand thespeed v proportiona1 to a-tunctionbf as in the Fig. 5

embodiment, for determining the angle 6, and continuously transmits thevalue of E to the impu1se mechanism duringthe pull-out.

' The release impulse mechanism 306 may con- The static p ess p at theaimmflaltimdeihfiso oianadr ng and siiht aetin ..me h n m.a

-,'., is. .detectedv by means; one, manometer 3|! pneuniaticallyconnected withthe'Pitot-static tube of the aircraft and the staticpressure on e gisting at the level of the target is set into theinstruin 'theFig."'5 embo'dimnt,.,tii. i twoscon'tacts which complete anelectric circuitwhenthe'above irequati'onaiisssatisfied. :=In-.thaticaseflhoweveriian extra difierenti al is needed, since the numberof ment by means ,of---a manua1' n lT-heit35 terms in the equationwiswnow four instead of calculating device 3I6 into whichstheoiltputs of7: e manual -statie' pressure control;.3:l 8. andautomatie staticspressure -detector 3i 1.-are: feci;-:.prod-uces -anoutputiproportionaltoa-ifunctiomof h,

three.

eWi-th th$foreg0 g-assan out1ine==ofi the oper- ---ations perforrned by:the instrumentof -this invention a detailed description will now begiven in accordance with the Formula fiii.'. ih=f('l7llp HA0 of specificdevices wherein the principlesmf the The output of a this computationsisiedeinto; anoth ercompute1* 34 5 salong withsa-njcutput which is a.function of the dynamic pressure-rains; derggaeeted by the mangrneterfil I, and the output of invention may be carried out, beginning with aninstrument which conresponds to that diagrammed in Fig. 6.

In the instrument shown in Figs. 6 and 9 the this computer 3l5 is inturn fed into another-r calculation of e follows-the pattern below:

computer 3l2, along with-,.i;he:;o-utput sofa -gyroesc neiel'zierectedeaedi neeee i; n et fli ht at theeinst e h .presseat i ctuabutton.

The resultant computedby ---the-device==-3 I 2* is modified by meansoiamanual. control 3l3 which isadjusted in accordance with prevailing windonditions. The -ang1e A= is-measuredby -means pilot'presss;theactua-ting button) g-and-sinoathe sponds to a functiomof eand theresultant-comiitedb y the calculator illacorresponds-to a funciojn -of-a,-the' three outputs tnamely that from he gyroscope T -correspondingt0- A, -the-.a=011t put and the e-output)--' may be -fed intoan adding"*ethat a release impulse :is generateda when -the Thisdiilerentiatingmechanismis -represented in 1='ig;gre -7 in whichgthecutput of -the computer "5396 is assumed to actuate-an-arm fibthrough gap angle-corresponding-to 11+ sfWh-fle a-- gyroscope 'Ic ismounted-in gimbals 1b: ona frame lw fixed w ith respeet -to;-;the--aircraft-and adapted to be uncaged by mechanism- 1deactuated -by-z therelease button. The gimbals lb-actuate an-arm'-6a,

..- II Measured in the instrument:

Quantities in the instrument I Manually set:

- Quantrtrcspq', G, c, u, gyroscope'datumsetting presumed-known.

ith mm? Measured by 2011 5 sgxroscepe accelerometer. .55

III Calculated in the instrument by calculating mechanisms: 1 I

Quantities n g Y e; a, a. a a

According to equation... xi xii x v viii vi (xv 1..-Th --/h-mecitani m IThe known static pressure at the levelof the .65 target is set inthe-bombing instrument by the eoam in relation to the pressurep'o bymeans of a driver attached to said nut 30.

On an extension of said square shaft 33 there is a gear wheel '31;coaxially attached,

which meshes'with a gearwheel 38' attached to theshaitof an electricmotor-'39.

A cam"follower 40 on a feeler arm 4! co'ntactsthesurface of the 7h cam32, said feeler armbeing pivotally mounted ona" p'in'42 attached to thebase of the instrument so that said cam follower mean swing in a planethrough the center line of the square shaft 33. A tension spring 43 isconnected tosaid feeler arm 4| and to a pin 44 attached to thecenter ofone side of an aneroid 45 The other'side of said aneroid-is rigidlysecured'to the base of the instrument by means of a pin 45. The aneroid45, which is exhausted of air, is actuated by the pressure of the airsurrounding the aneroid. Said pressure is kept equal to thestaticpressure p by a conduit 48 from the Pitot static tube 41 to theinterior of the instrument and the inside 'of the instrument is isolatedfrom its surroundings by an airtight cover 49, said cover being shownmostly cutaway in Fig. 9.

As the static pressure varies the pin 44 is displaced, said pin therebymoving one end of a contact arm 50 which is pivotally mounted on a pin5| attached to thebase'of the instrument. Small movements of.the'contact arm cause'its "other end to swing into engagement with Toneor the other of two electrical contacts 52 and 53 attached to the baseof the instrument. The contact arm 50 is connected to thepositiveterminal 2! of a source of current 2l2 in the aircraft and the contacts52 and53 are connected to the terminals 54 and 55 of a reversible motor39. Said motor is provided with a third terminal 55 connectedto thenegative terminal 2 of the source of current ZIZ.

direction when there is a 'difi'erence'of voltage I between theterminals 54 and 56 and inthe other direction when there is a differenceof Voltage between the terminals 55 and 55.

If it is assumed that the altitude of the aircraft is decreasing; thestatic pressure actuating the aneroid 45'will displace the pin 44towards the aneroid 45. Asa result the contact arm 5!) will engage withthe contact52, thereby closing the circuit to the terminal 54 on themotor 39. The motor now starts to rotate in one direction. therebyturning the three-dimensional cam 32. The cam 32 is. of such shape thatits turning causes, the feeler arm 4! to stretch the spring 43 until thespring force overcomes the influence of the increased static pressureand the pin 44 returns to its zero position wherein the circuit throughthe contact arm 50 and the contact 52 is broken and the motor 39 stops.This course of events will be repeated as long as the altitude isdecreasing. thereby keeping the stretching of the spring 43 in correspondence to the static pressure p. Conversely, as the altitude of theaircraft increases the spring 43 will slack in a corresponding way.

keeping the balance between the aneroid and the spring by. means of acycle of events the reverse of that just described and involving thecontact 53. I

The setting of a pressure 130 by means of the knob 25togetherwithuthepressure'p actuating the aneroid 45 determines the anglethrough whichthe 'yh cam. 32 must be turned to cause the contact arm 50to arrive at a position in The reversible 1 3 motor 39 is so designedthat it rotates in one which it does not contact either contact 52: or53.

It is evident that it is possible to give said 771 cam such a shape thatits-turning angle is pro portional to a desired function of thevariables poand p. In the instrumentthe shape of the h cam is socalculated and manufactured that said angle is proportional to themagnitude of 1 11 in Equationxi'. j

Coaxial with and attached -to the square shaft 33 there is a gear wheel51 meshing with 'a rack formed 'onthe' under side of a slide 58.

Said slide '58 "(the 'yh slide) is 'endwise' movable along-a guide 59attached tothe base of the instrument so that the displacement of the771, slide will be proportional to the magnitudel'r h.

2. The q-mechaaz' sm Anotherguide 55 is attached to the base of theinstrument at a right angle to-the guide;59 and along it another slide6| ismovable. The upper side of said slide 5| is-formed as afrack whichmeshes with a gear wheel '62 coaxially attached to a square shaft 63carried in bearings 64 and 55 in base of the instrument. An electricmotor 66 turns saidsquare shaft 63 by --means ofgear wheels 51 and68;-Slidably but non rotatably mounted on the square shaft 63 is athree-dimensional cam 69, the q cam,

The axial displacement of the q cam depends on the-movement of thefeeler arm 4|, the free 5 end of which is drivingly connected with the qcam. A feeler arm Hi, pivotally mounted on a pin H fixed in the base ofthe instrument, 3 contacts the surfaceof the q cam fifi. .One end p thesource of current.

means of a pin 15. connected with one end of a contact arm 15,

of a tension spring 12 is connected to the feeler arm 1!! and its otherend is connected to a pin 13 which is attached to thecenter of one sideon an aneroid '14, the other side of said aneroid beingfattached to thebase of the instrument by Oneend of said pin 13 is said contact armbeing pivotally mounted on a pin 1 attached-to the base oftheinstrument. A. small displacement of said contact armfflfi will swingit into engagement with one of two contacts 18 and TBQattache'd to thebase of the instrument, said contacts beingconnectedto the terminals 80and BI respectively of an electric motor 56, while the contact arm 75 isconnected to the positive terminal 210 of the source of current 212. Thethird terminal 82 of themotor 56 is connected to the negative terminal2H of e The total head pressure from. the Pitot static tube 4'! iscommunicated via the conduit 83 and a bore in the pin 15 with which theconduit communicates, to the interior of the aneroid M. Because saidaneroid has [above under 1. 59; thus depends on two variables namely theimpact pressure qt and the displacement of the 'feeler arm 4|,

which displacement depends upon the 'pressure p, as described above;hence the turning angle of the q cam 69 will be a function of themagnitudes (1c and p as variables, and

17' tively. Furthermore the shape of the el cam 93 is such that theturning angle of said shaft I24 will be proportional to the value e1according to the Equation v. w

6. 'The au-mechanism A feeler arm I21 pivoted on a shaft I28 carr ied inbearings in the base of the instrument, contacts the surface of the Bucam '92 thus getting an angulardisplacement depending on (pa and Y. Saidfeeler arm I21 has a straight slot along which a'pin I29 is slideable.tached to a rack I30 which is mounted for endwise reciprocation in arectangular hole in a slide I 3I. Theslide I3Iisin turn' slideable atright angles to the direction of reciprocation of the rack I30 along aguide'l32 attached to the base of, the instrument. The slide I3I can bedisplaced along a guide I32 bya lever 22'I, pivoted to" a 'pin 222secured to the slide; A threaded shaft"l33, parallel to said guide I32,is carried in bearings I34and I35 in the base of the instrument and isrotated by means of a graduated knob I 36 for setting the wind componentu. Rotation of the shaft I33 axially displaces the follower 223 thereonwhich carries a finger engaged'in a longitudinal slot in the lever 22I,so that said lever is thus swung in proportion to rotation of the windcorrection knob I36. A prolongation of the square shaft 63 on which theq cam is mounted"h'a's anon-linear thread and a follower 224 which has afinger engaged in another. longitu dinal" slot in the lever 22I. In zeroposition (a' 'i0) the lever 22I is perpendicular to the guide I32, andthe pin I29 concentric to the shaft pivot I28. When u is set, thefollower 223 will move a distance proportional to u, and the slide I3I,a distance proportional to u and a factor depending on q. Furthermorethe rack ISII will be displaced," in" relation" to the slide I3I, adistance proportional to'u, said factor depending on q and 'a factordepending. on the actual angle of the feeler arm I21. Thethread for thefollower 224 and thet cam 92 are cut in such a waythat said factorswill'be, respectively, 1 and z in equation viii. Thus thedisplacement'of the rack I30 will be proportionalto the value ,iLh/VQWHVZd/W/ t i. e. proportional to the angle 611' in-Equation viii if k/vis considered as approximately constant. The rack I30 rotates a gearcylinder I38 on ,a shaft I31 so that said shaft gets an angulardisplacem'ent'which is also proportional to Bu;

, The fie-mechanism crank-like shaft I39, rotatable inbearings I40 andMI in the base of the instrument, has at itseccentric end a feeler armcontacting the surface of the 50 cam 94. The turning of said shaft I39is transmitted to a slide I42, slideable along'a guide I44 by reason ofthe fact; that the under side' 'of-the slidegis partly shaped as a rackand mesheswith a'gearwheel I43 onshaft I39, A rack I45 is endwiseslideable in a1 rectangular hole insaid slide I42 perpendicular to theguide I44; The rack I45 meshes with and isslideable axially along a gearcylinder I41. Said gear cylinder I41 is mounted on a shaft I48,"carried'in bearings I49 and I50in the baseof the instrument, andhaving agraduated. knob II by means of which the dragcoefficient cof the bomb in"question maybe manually set. 5

Another slide'l52 e estimations insignia Said pin is at I. Said slide ispartly shaped as a rack which meshes withagea'r wheel I53 attached toextension of the square shaft 63. Arac'k' I54 'i's slideable in arectangular hole'in the slid'e I52, perpendicular to the guide I44, andmeshes with a gear cylinder I56 on a shaft I51 carried in bearings I58an'd I59 in the baseof the instrument. An arm 'I6I, havinga-I straightlongitudinal slot, is pivotally mounted atone end on a pivot I60 in thebase of the instrument. Along the slot in the arm pins I46 and I 55 onthe racks I and I54, respectively, are slideable; Said slot is soarranged that the center lines :of the pins I46 and I and'the-shaftpivot iI6'0 are always held in a straightline.. When the arm I6I isparallel to the guide I44 theipins I46 and I55 arein positionswhich arelhereinaftercalled their zero positions. i

As described above the square shaft 63' together with the gear wheel I53will be turned through an angle proportional to the value q. Furthermorethe gear ratio between the gear wheel I53 and the rack of the slide I52is so chosen that the distance between the centers of the pin I and thepin I55 in zero position is proportional to the value q and the surfaceof the 6s cam 94 is so shaped that the turning angle aof the shaft I39will be reciprocally proportional to the function f1 depending on thevalue Yvand (pa in the Equation vii. In addition the gear ratios are sochosen that thedistance between the center of the pin I60 and the pinI46 in zero position is proportional to the value ,1 1" r The distancewhichthe pin I46 is displaced from its zero position, when setting theknob I5I,,. is arranged to be proportional .to the value c. 7 It isevident that, as a result of the geometry of the device, the pin I55will be displaced a distance from its zero position proportional to ,thevaluetc according to Equation vii and consequently the turning angle ofthe shaft I51; will also be proportional to the value last mentioned.

8. The a-mechanism By" means of a graduatedknob I62- the gross weight ofthe aircraft has to be set manually. Said knob is attached to a shaftI63, carried in bearings I64 and I65 in the base of the instrument. Apa-rt of said shaft is threaded andis receivedin an internal thread in aslide I66, so that rotation o-fthe knob I62 displaces the slide I66along an extension of the guide 60. An arm I68 is pivoted on a shaft I61inthe base ;of the instrument and has a straight slot along which pinsHI and I12, attached to racks I69 and I10 respective1y, are slideable.Eachgof said racks meshes with one of two gearcylinders l13 and I14respectively, Said gear cylinders together with their shafts, I15 andII6respectively are m edm, h arines- 1 net- .119, 80.. -v spectively.Said slides, racks, arm, gear cyline ders and shafts function inthe sameway as those i in the tiemechanism described above 1111-. den heelm m, 8:1 i el esi ee; i ere aanai orea en 'lhefiis ellqfi tw ei lh l n tti pvot I6 n tne in: III wi be proportional to the value q andthe distance;

between said shaft pivot I61 andthe pin I12- will be proportional to thevalue G or G/F.

The shaft I15, which is controlled byan accelerometer mechanism, turnsin'propor't'idn to the acceleration n of the aircraft. I Said accelontothe end of the steel ban pivotedon a shaft I15 and carrying aweight.I8I. atits freeend. Tosaid arm I82 there is attached one end of atorsion spring I83, the other-end of which is attached to a gear wheelI84. Said gear wheel is coaxial with and secured to said shaft I15 andmesheswith a gear wheel I85 on the shaftof an electric motor I86. Acontact arm I81 .is attached to the arm I82 so as toengage either of twocontacts I88 and I89 upon smalLmovements' of;'said arm I82. Saidcontacts I88 and I89 are attached to the base oftheinstrument andconnected to the terminals; I 90' and I 9 I" respectively of the motor;I 86. The third terminal I92of the motor is connected to the "negativeterminal 2II of. the source of current 2I2.. &.The contact arm. I81 isconnected Qerometer mechanism. comprisesyan arm .I82,

to the positive terminal i2I0..of said source of v current. v

' When the-acceleration .11, of the aircraft is increasing, the WeightI8I will be pressed down. As a result the contact arm I81 will engagethe contact I88, whereby the motor I86 starts twisting. the spring I83ina direction to cause its torque to. raise the Weighted'arm I8I,breaking the circuit through the contact arm I81 and the contact. I88.This course of events will be repeated as. long. as the accelerationisincreasing. When the acceleration is decreasing the movements arereversed.

The torque of said springrequired to balance the weight .I8I influenced,by the acceleration forces during the pull-out. will be proportional-tothe value n. According to the properties of the spring I83 the turningof the shaft I15 will also be proportional to the value n. The turningof the shaft I16, by the slidemechanismfil, I66' I14, will. thus beproportional. to the value (ll-us) inEquation-xiii.

I V 9." [The total calculator v CoaxialIy-secured to thegear wheel I62is a wheel I93- to the periphery of which a steel band I94 is attached.'I-heshafts I24, I31, I51 and I'162each-have a coaxially attached gearwheel I95, I96, I91 and. I98 respectively, each one of the gear wheelsmeshing with a rack I99, MI and 202. Each of the racks is endwise'slideable-along its own guide 203, 294, 2Ii5 -and-206, respectively,attached to the base of the instrii mentand parallel toea'chother. Eachone of said fourracks carries in bearings a rotatable Wheel-291, 298,289 and 2 I3 respectively around which" the steel band I94 is trained inzigzag. The steel 'band I94 also passes over an idler wheel- 2 I4,carried on a shaft secured to 'the base ofthe instrument' andalso over aWheel 2I5, to which it is-attached at a' point on the periphery of thewheel. Said wheel 215 is rotatably mounted on an extension-of theshaftpivot 1840fthe'g'yroto "adr'aw spring2I 6, one-end of which is'hooked v dand'theother end tothe baseof th'einstrument.-- '1 1' will;-seen-thatthe steel "band I94 will mjove; a distance equal to theperipheric'al dis-- placement of the wheel I93 'plusftwi-ce thealgabraic; sum of the'dis'placements of the rack s199, m; 201 and 202.As described above, the turning anglesof the following shafts areproportional tothe following'values: Shaft 95 to valuea,.'

Shaft I24 to value e, Shaft I31 to value 811, i

gageable with a contact 2 I8 attached to the gim bal I05 of thegyroscope. The contactarm 2I1'is electrically connected to one of theterminals of the bomb release mechanism 24, the other terminalof. whichis connected'to thenegative ter minal 2II ofsource' of current .2I'2.'Said bomb. release mechanism is of such designthat it re-'- leases thebomb 3I when there is'a voltage difference between its terminals. Thecontact 2I8 is connectedto a terminal 229 of the actuatingbutton 23.Said actuating button is'so designedthat the terminal 220 is connectedto another ter; minal .219 when the button is pressed and the terminal2'I9is connected to the positive terminal ZIO'of the source of current2I'2;,.;. I As described in connection with the 111-3101321194- tusunder section 4 above, the angular movement of th'e gimbal I is equal toTimeasured from the caged position. Furthermore'the Wheel2I'5 has such adiameter, and thefastening angle bee tween the contact arm 2" and thesteel band I94 is so chosen, that the angular diiferencebje tween thecontact surfaces of the contact arm 2I1'and the contact 2I8 during their'movements around the axis of said shaft pivot I04 is equal to the angleB=$, +i +ei+6c+8u according. to

1'0.- The application of the bombing instrument shown in Fig. 9 1 I.

Af r setting of the knobs 25,162,15I "andijas and' the' proper uncagingof. the gyroscope with the knob I89 the. bomb-aimer-pilot has to aim atthe t'arget with the optical axis 20 of the'sight,

provided that 'the attack'is made parallelto the wind direction. Whenthe aimingis satisfactory, he presses the actuating: button 23 andstartsth'e pull-out straight forwards and with the wing tips level.During thepull-out, due to the movements of the contact arm 2I1 and thecontact 2I8 in relation to each other, said angle 8 between the contactsurfaces will decrease and the contacts engage when 5:0. At that momentthe bomb bomb .3I released. V v V After the release the bomb-aimer-pilothaste release mechanism 24wi11 b'e energized v ar ld the stop pressingthe button 23,which returns to its Fig.i10:shows an alternative designof aportion ofithebbmbing instrument according to :the in.

.vention .shown, in Fig. 9 andcorrespondingato that diagrammed in Fig.5. The parts #I593r209. 2I.3:-.2 I8i'n Fig. 9 are replaced by225-25Iin1i'ig.

10. The principal difference between the alternatives is the fact that asecond gyroscope is added in Fig. 10, measuring the angle of pull-out Aand that the first gyroscope only measures the angle-of dive e.

According to Equation xiv the Equation xv can be written.

For the measuring of the angle (be, needed only for the terms a, 611 and6c in Equation xvi, there is a gyroscope Il06 with a caging device,designed in the same manner as described above in relation to Fig. 9.Thus, the turning angle of the three-dimensional cams 9 2, 93 and 94 iscontrolled by means of said gyroscope.

A wheel 225 is coaxlally attached to the shaft I16, which, as describedabove in relation to Fig. 9, turns through an angle proportional to thevalue a. Gear wheels 226, 221 and 22B are attached to the shafts I24,I31 and [5! respectively and each of said gear wheels meshes with a rack229, 230 and 231 respectively, each of said racks being slideable alonga guide232, 233 and 234 respectively fixed in the base of theinstrument. Each of said racks 229, 239 and 2M carries a freelyrotatable wheel 235, 236 and 231 respectively. Referring to thedescription of the Fig. 9 embodiment above, it will be seen that saidwheels will be displaced a distance proportional toe, in

and 50 respectively. Attached to the periphery of the wheel 225 there isa steel band 238 runnin in zigzag around the wheels 2311, 236 and 235,and then; around-two wheels 23.9 and 240, rotatable on journals fixed inthe base of the instrument and around the wheel 24!, journaledon a pivotshaft 242. From said whee1'24l, t which it is attached at a point, thesteel band 233 continues to a tension spring 243, one end of which ishooked on to the end of the steel band 238 and the other end to the baseof the instrument.

The gimbal 244 of a gyroscope is rotatably carried by coaxial pivotshafts'242 and 246 fixed in the base of the instrument and parallel tothe pivot shafts I03 and! of the gyroscope 105-406. Said gimbal .244carries the rotor casing 245, the arrangement being similar to that ofthe gyroscope I05+lll6. 'A.funn'ele d disk 249 is attached coaxially totherotor casing 245; A pm 248 is endwise pressed against said disk 249by a spring (not shown in the figure), there! by caging the gyroscope.The pin is actuated by a solenoid 241 which withdraws it from. the disk249, thus uncaging the gyroscope, when the solenoid is energized. Theterminals of the solenoid are connected to the actuating button 23 andthe source of current 212 in such a manner that the solenoid will beenergized when the actuating button 23 is pressed. It will be seen thatthe angular movement of the gimbal 244 will be equal to the angle A,measured from the caged position of the gyroscope. Attached to thegimbal 244 is a contact arm 259, which can engage another contact arm25l, attached to the wheel 24].

In a manner similar to that described for the bombing instrument shownin Fig. 9 the angular difference between the contact surfaces of thecontact arms as they move around the axis of said shaft 242 is arrangedto be equal to the angle 5i+5u+5c+G-A=I3 according to Equation xvi. In asimilar way as described above with reference to Fig. 9 the contact arms25!! and 25] close a circuit through a bomb release mechanism 24, whenthe actuating button 231s 22 pressed and the angled is equal to zero.The manner of using thebombing instrument shown in Fig. 10 's exactlythe same as that of the bombing instrument shown in Fig. 9. In, additionto the above mentioned embodiments of the bombing instrument theinvention contemplates several other variations. For instance, certainsimplifications of the instrument shown in Figs. 9 and 10 are possible,the price of which, however, is a-reduction of the degree of accuracy ofthe instrument, or a limitation of its range of application. v

One simplification is to replace the 611-mechanism which includes thethree dimensional 6n cam 92 by extending theshaft I31 to the outside of;the instrument and setting the wind speed directly on said shaft bymeans of a knob. This simplification is based on the assumption that thefunction In in Equation viii is constant which is approximately trueunder certain conditions.

A second simplification is to eliminate the entire" lie-mechanism whichincludes the threedimensional 5c cam 94 by assuming the value c asconstant in Equation viiand standardizing the value q as a function ofthe value :Y and ipa, the latter approximationbeing possi-j ble, due tothe fact that the percentage variations of q from normal values aresmall. Thus the value 60 inEquation vii will only be de pendent on thevalues Y and we and is apt to beincluded in the value i by modifying the1 cam '93. It will be understood that the simplification indicated wouldlimit the types of bombs which might be used with the apparatus.

A third simplification of the instrument is possible, due to the factthat the influence of the value p in Equation xii is small, whereby. thethree-dimensional q cam 69 can be replaced by a plain cam attached onthe shaft t3, i. e. q is put equal to a function of qc only (p constantorstandardized as afunction of do).

A fourth simplification of the instrument is possible, due to the factthat the value 771. in Equation xi canbe taken as approximately equal toa function of the value (pop), so that the three-dimensional yh cam 32can be replaced by. a plain cam on the shaft 33. In this case the screw29 andthe nut 30 have to be replaced by a device arranged to displacethe pin 42 in a direction parallel to the spring 43 a distanceproportional to the value 100. i

The gyroscope caging device "19-! I4 in Fig. 9 and Fig. 10 can bereplaced or complemented by an automatic erection device for the purposeof erecting the gyroscope rotor axis to vertical position and keeping itthere. There are several types of such devices known in the art.

The embodiments of the bombing instrument shown in Fig. 9 and Fig. 10have, as described above, several reversible electric motors for thepurpose of servo-operating the various mechanisms.

Many other types of servo-systems are well understood in the art andseveral of them are suitable for the purpose.

' The instrumentalities for the manual settings to be 'made directly onthe main unitof the in;

